The present invention concerns the field of optical guides or optical guidance devices, and more particularly guides for transporting an image without deformation. These guides may in particular be used for building ocular-vision optical systems, more commonly referred to as informative spectacles.
An optical guide generally comprises an injection section by means of which the light beam transporting an image is introduced. The light beam transporting the image comes from a source that may be a matrix of pixels of the LCD (Liquid Cristal Display) type illuminated by a light source or a source of the OLED (Organic Light-Emitting Diode) type. The light beam next passes through an optical system for obtaining a collimated beam, meaning the rays of which are substantially parallel. It is also said that the image is thus carried to infinity. The collimated beam is then introduced into the injection section of the optical guide.
The optical guide enables the light beam to propagate by total internal reflection, optionally by means of a specific treatment of the walls of the optical guide. The light beam thus propagates as far as an extraction section enabling it to emerge from the optical guide. The extraction section may consist of a reflector terminating the optical guide in an inclined plane.
The patent FR 2 925 172 B1 describes an optical guide provided with an extraction section consisting of reflective microstructures formed on the surface of the optical guide. These microstructures consist of prisms having an angle enabling the light beam to emerge from the optical guide. The microstructures are spaced apart by interstitial spaces formed in the extension of the surface of the optical guide. These interstitial spaces, meaning not covered with microstructures and fitting between them, are transparent and thus allows obtaining see-through effect. This enables seeing the image transported by the light beam, as well the scenes beyond the optical guide. These interstitial spaces however imply a phenomenon equivalent to a diffraction through a slot, which causes interference on the vision of the surrounding scenes through the optical guide.
It is desirable to overcome these various drawbacks of the prior art.
It is in particular desirable to provide a solution that enables a user of the optical guide to see an image, injected into the guide, so as to be superimposed on the scene taking place beyond the guide, and this while limiting the interference perceived both on the injected image and on the vision through the optical guide.
It is in particular desirable to provide a solution that overcomes the phenomenon equivalent to a diffraction through a slot inherent in the solutions of the prior art.
It is in particular desirable to provide a solution that is simple, reliable and inexpensive to manufacture.